Examples of a substrate on which an electronic component is mounted (hereinafter, referred to as a “substrate”) include a substrate on which a BGA (Ball Grid Array) is mounted and a substrate on which an LGA (Land Grid Array) is mounted. In these substrates, a terminal, which is an electrical connection portion of a component, is located between the substrate and the component, and it is difficult to observe, by a conventional visual inspection apparatus using a camera, the state of the solder for joining the component and the substrate. Accordingly, a technique is presented, in which the three-dimensional shape of the solder in a joint portion is reconstructed into an image based on transmission images of the solder obtained by radiating X-rays onto a substrate from multiple different directions such that the inspection is performed by using a cross-sectional image in which any cross-section of the solder has been cut out (see Patent Document 1).